In the art of liquid development one of the major problems in the past has been to obtain a required degree of fineness of the developers to insure that there is no sedimentation during storage and that there is highly effective development with high resolution, conditions not possible where the developer is of a relatively coarse nature.
In the past, the method used for the production of the fine powders suspended in the carrier liquids was effected by grinding the developer medium in ball mills or the like, such grinding taking many days to produce ultra-fine developers of high quality.
This grinding was also used as a means of applying control coatings to the toner particles by carrying out the grinding in the presence of resins or other control means which served to wet the particles as they were ground to the required fineness, the control medium being in liquid form, this remaining as the outer phase which coated the particles as they were ground to the required fineness, this principle having been fully explained in earlier patents by the same Applicant and forming the basis of highly satisfactory liquid developers.
It will be realized that the finer the developers the more readily the developer particles can be suspended in an insulating carrier liquid, and by coating or surrounding the particles with the control medium, such as an insulating resin, coagulation of the particles was largely prevented because all particles were of similar polarity and the particles therefore tended to repel each other when freely supported in the liquid.
Various problems however have been encountered in the production of developers by the methods used at the present time, and an object of the present invention is to provide an improved form of manufacture of developers and also an improved form of developer itself which will have characteristics which are advanced in effectiveness over those known heretofore.